x86: add is_errata100 helper to fault_32|64.c

Further towards unifying these files, add another helper
in same spirit as is_errata93.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/mm/fault_32.c

@@ -286,6 +286,22 @@ static int is_errata93(struct pt_regs *regs, unsigned long address)
 	return 0;
 }
 
+/*
+ * Work around K8 erratum #100 K8 in compat mode occasionally jumps to illegal
+ * addresses >4GB.  We catch this in the page fault handler because these
+ * addresses are not reachable. Just detect this case and return.  Any code
+ * segment in LDT is compatibility mode.
+ */
+static int is_errata100(struct pt_regs *regs, unsigned long address)
+{
+#ifdef CONFIG_X86_64
+	if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) &&
+	    (address >> 32))
+		return 1;
+#endif
+	return 0;
+}
+
 void do_invalid_op(struct pt_regs *, unsigned long);
 
 static int is_f00f_bug(struct pt_regs *regs, unsigned long address)
@@ -566,6 +582,9 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
 		if (is_prefetch(regs, address, error_code))
 			return;
 
+		if (is_errata100(regs, address))
+			return;
+
 		if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
 		    printk_ratelimit()) {
 			printk(

arch/x86/mm/fault_64.c

@@ -256,6 +256,22 @@ static int is_errata93(struct pt_regs *regs, unsigned long address)
 	return 0;
 }
 
+/*
+ * Work around K8 erratum #100 K8 in compat mode occasionally jumps to illegal
+ * addresses >4GB.  We catch this in the page fault handler because these
+ * addresses are not reachable. Just detect this case and return.  Any code
+ * segment in LDT is compatibility mode.
+ */
+static int is_errata100(struct pt_regs *regs, unsigned long address)
+{
+#ifdef CONFIG_X86_64
+	if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) &&
+	    (address >> 32))
+		return 1;
+#endif
+	return 0;
+}
+
 void do_invalid_op(struct pt_regs *, unsigned long);
 
 static int is_f00f_bug(struct pt_regs *regs, unsigned long address)
@@ -568,14 +584,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
 		if (is_prefetch(regs, address, error_code))
 			return;
 
-		/* Work around K8 erratum #100 K8 in compat mode
-		   occasionally jumps to illegal addresses >4GB.  We
-		   catch this here in the page fault handler because
-		   these addresses are not reachable. Just detect this
-		   case and return.  Any code segment in LDT is
-		   compatibility mode. */
-		if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) &&
-		    (address >> 32))
+		if (is_errata100(regs, address))
 			return;
 
 		if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&